Technical Field
The present invention relates to a channel estimation technology, and more particularly, to a method for estimating cable length in an Ethernet system and a receiver thereof.
Related Art
In an Ethernet system, use of channels can be better detected and controlled if cable length information and cable status are provided. Therefore, a lot of manners for estimating a cable length have been proposed, for example, estimating a cable length by measuring energy of a received signal, or estimating a cable length by observing a relation between spectrum of a received signal and the cable length. Although many manners at present can be used to provide cable length information of an ultra-high-speed Ethernet system, these manners fail to have the following three elements at the same time, i.e., stability, simple calculation and high accuracy.
For example, the manner of estimating a cable length by measuring energy of a received signal is easily affected by different power of a transmitting end, and thus cannot maintain the same effect in various environments and cannot provide good stability.
The manner of estimating a cable length by observing a relation between spectrum of a received signal and the cable length uses a channel response ratio of 6 MHz to 43 MHz for cable length estimation. It is found according to a simulation result that the accuracy thereof is quite high, but the problem lies in that the actual hardware implementation requires too high cost. As calculation of DFT (Discrete Fourier Transform) of many points is required for accurate calculation of components of 6 MHz and 43 MHz, this involves a large number of multiplications and additions, so that the IC area becomes large and the cost increases, which is difficult to meet the actual demand.